珠江口盆地白云凹陷荔湾深水扇砂体分布预测

发生于13．8Ma前的强烈海退使得珠江口盆地白云凹陷发育了大型的海底峡谷-断裂坡折型深水扇，浊流沿海底峡谷将碎屑物向凹陷内搬运，在海底峡谷内充填形成浊积水道砂体．在断裂坡折带之下快速卸载形成前积砂体。根据深水扇地震响应特征研究发现，沿着古水流方向，深水扇自断裂坡折带附近向白云凹陷呈进积充填；在垂直古水流方向上，深水扇砂体呈丘状充填。以分隔深水扇的底积层作为等时面，可将荔湾深水扇划分为3期相互叠置的朵叶体，通过地震属性分析等储集层预测手段．预测了各期砂体的分布；扇体发育过程中．由于重力作用，粗碎屑首先在坡折带下降盘附近卸载，细粒的泥质沉积物以悬浮搬运的方式被带到侧缘或更远的下扇区沉积下来．因此，朵叶体的主体部位富砂，两翼及前缘末鞘一带富泥。圈8参9

Prediction of Liwan deep submarine fan sand body distribution, Baiyun Sag, Pearl River Mouth Basin

A deep submarine canyon and turbidity channels were developed along the hanging wall of fauhing break zone as a result of the 13. 8Ma regression. The deep submarine fan was developed in the footwall near the outlet of the canyon. According to the seismic response characteristics, the fan is characterized by th, e progradation reflecting seismic facies parallel tO the direction of paleocurrents and by the mounds reflecting seismic facies perpendicular to paleoeurrents. The fan can be divided into three period overlapping lobes based on the prograding sequence relationship. Based on the seismic facies analysis, the sand body distribution of the fan is predicted. During the development of the fan, coarse fragments unload firstly near the footwalI of the fauhing break zone due to gravitation, and fine-grained sediments are taken in suspension to and deposit in the edge or further areas, so the main part of the lobes is rich in sand and their edges and front ends are rich in mud.